Reversible Trimmer Head Spool With Inclined Teeth Rings

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Solution Overview

Problem

Existing trimmer heads are not efficiently reversible to accommodate drive shafts rotating clockwise or anticlockwise, requiring complex mechanisms for correct operation and leading to inefficiencies in line rotation and unwinding.

Innovation Solution

A trimmer head design featuring two interchangeable ring members with inclined teeth, allowing the spool to rotate reversibly with respect to the housing, enabling the trimmer head to be mounted on trimmer apparatuses with either clockwise or anticlockwise rotation by selecting the appropriate ring member for torsional coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single set of inclined teeth is provided on the housing portion, then the structure is simple, but the trimmer head cannot operate on drive shafts rotating in either direction

Engineering Contradiction:

Improvereversibility of trimmer head operationVSAvoidstructure of housing portion

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The housing portion is divided into two separate ring members, each with a different set of inclined teeth configured for a specific rotation direction. This segmentation allows the user to select the appropriate ring member based on the drive shaft rotation direction, achieving versatility while keeping each individual ring member structurally simple

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The housing portion is designed to accommodate both clockwise and anticlockwise rotation directions through the provision of two interchangeable ring members. This multi-functionality allows the same housing to work with drive shafts rotating in either direction, eliminating the need for different housing designs

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If two sets of inclined teeth are provided on opposite faces of the housing portion, then reversibility is achieved, but the manufacturing complexity increases

Engineering Contradiction:

Improvereversibility of trimmer head operationVSAvoidmanufacturing of housing portion

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Instead of manufacturing a complex housing with two sets of inclined teeth on opposite faces, the design segments the housing into two separate, simpler ring members. Each ring member is manufactured independently with a single set of inclined teeth, significantly simplifying the manufacturing process while achieving the same reversible functionality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inclined teeth are extracted from the main housing body and placed on separate, removable ring members. This extraction allows the housing to be manufactured as a simpler component, while the ring members can be manufactured separately and attached as needed, reducing overall manufacturing complexity

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If the spool is prevented from rotating in one direction by inclined teeth, then correct unwinding is achieved, but the spool cannot rotate in the opposite direction for reloading

Engineering Contradiction:

Improveline unwinding processVSAvoidrotation direction flexibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The design inverts the approach by providing two different ring members with inclined teeth oriented for opposite rotation directions. By selecting the appropriate ring member based on the desired operation (unwinding or reloading), the system achieves ease of operation for the specific task while maintaining versatility through the interchangeable ring members

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design allows for efficient and reversible operation of the trimmer head on both clockwise and anticlockwise rotating drive shafts, simplifying the process of line unwinding and reducing the risk of incorrect assembly, while using high-quality materials only where necessary to minimize wear and cost.

Implementation Method 1

a spool axially movable inside the housing and biased by a spring which co-acts with the spool and pushes the spool to a first operating position

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 2

the first set of inclined teeth and the projections are configured such that when the first ring member is torsionally coupled to the housing or to the spool, the first set of inclined teeth and the projections prevent rotation of the spool relative to the housing in a first direction and cause an axial displacement of the spool with respect to the housing against the action of the spring

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Data Source

PatentUS11109530B2Trimmer head and spool for a trimmer head

Publication Date: 2021.09.07 ARNETOLI MOTOR

AI summary

The trimmer head (1) includes a housing (3) and a spool (5) that can be housed in the housing. A pair of ring members (35A, 35B) with teeth inclined at opposite inclinations can be selectively coupled to the head, to engage the trimmer head (1) in combination with trimmer apparatuses having engine that rotates selectively in a clockwise or anticlockwise direction.